Pilonidal Disease

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

Pilonidal disease is a chronic infection of the skin and subcutaneous tissue in the natal cleft (between the buttocks), often caused by ingrown hairs leading to abscess formation or sinus tract development.

Aetiology

  • Hair accumulation: loose hairs penetrate the skin, triggering an inflammatory response.
  • Friction and pressure: prolonged sitting or repeated trauma exacerbates the condition.
  • Bacterial infection: secondary infection with skin flora such as Staphylococcus aureus and anaerobes.

Pathophysiology

  • Hair enters the skin, leading to an inflammatory reaction.
  • Cyst or abscess forms as the body attempts to isolate the foreign material.
  • Over time, sinus tracts may develop, leading to recurrent infections.

Risk factors

  • Male gender (higher incidence due to coarser hair).
  • Age 15–40 years.
  • Obesity (increased sweating and friction).
  • Excessive body hair, particularly in the sacrococcygeal region.
  • Prolonged sitting or sedentary lifestyle.
  • Poor hygiene or excessive sweating.

Signs and symptoms

Symptoms:

  • Painful swelling or lump in the natal cleft.
  • Redness and tenderness over the affected area.
  • Foul-smelling discharge (purulent or serous).
  • Intermittent sinus drainage.
  • Fever (if abscess formation is present).

Signs:

  • Swelling or lump with an overlying sinus opening.
  • Pus or blood-stained discharge from the sinus.
  • Localised erythema and tenderness.
  • Fluctuant mass if an abscess is present.

Investigations

  • Clinical diagnosis: based on history and examination.
  • Ultrasound: used if an abscess is suspected but not clinically evident.
  • Microbiology: wound swab for culture if recurrent infection is present.

Management

1. Conservative Management:

  • Hygiene measures: regular washing and hair removal (shaving or laser hair removal) to prevent recurrence.
  • Weight management: reducing excess weight to minimise friction.

2. Medical Management:

  • Antibiotics: indicated if cellulitis is present (e.g., flucloxacillin).
  • Analgesia: NSAIDs or paracetamol for pain relief.

3. Surgical Management:

  • Incision and drainage (I&D): for acute abscesses.
  • Excision with primary closure: higher recurrence rate but faster healing.
  • Excision with secondary intention healing: preferred in recurrent disease.
  • Laser hair removal: reduces recurrence in chronic cases.

Referral

  • Routine surgical referral: for chronic or recurrent pilonidal sinus requiring definitive surgery.
  • Urgent referral: if an extensive abscess is present or the patient is systemically unwell.
GastroenterologymypanotesPilonidal Disease